The present invention relates to an iris authentication apparatus which authenticates an individual from his/her iris which adjusts the amount of light entering the eye.
Conventionally, as an iris authentication apparatus of this type, an iris authentication apparatus like that disclosed in WO 94/09446 (reference 1) has been used. This iris authentication apparatus cuts an iris portion in the form of a plurality of arcuated portions (see FIG. 23: arcs SO) from a sensed eye image (eyeball image), and extracts the features of an iris pattern by using a bandpass filter such as a Gabor filter, thereby generating a one-dimensional code (iris code) for each arc SO. Such iris codes are generated for a registration eyeball image and a collation eyeball image, respectively. The Hamming distance between the iris codes is obtained, and the authentic person is discriminated from others on the basis of the Hamming distance.
Note that the iris is a diaphragm which is located between the cornea and eye lens of the eyeball, has a pupil in the center, and adjusts the amount of light entering the eyeball. The sclera (the white of the eye) is located outside the iris. A pattern is formed in the iris after about seven or eight months of pregnancy and becomes stable about two years after birth. The pattern is kept unchanged throughout lifetime. The left and right eyes of even the same person have different iris patterns, which are hardly generically influenced. In addition, since the iris is an internal organ, the iris is robust against damage and allows authentication in a noncontact manner.
According to the iris authentication apparatus disclosed in reference 1 described above, however, since an iris portion is cut out in the form of a plurality of arcuated portions from an eyeball image and processing is performed for each arc SO, if a cutting error concerning arcuated areas (an error in the radial direction, in particular) occurs, the iris position where feature extraction should be performed by a Gabor filter varies depending on whether a registration eyeball image or a collation eyeball image is to be processed. As a consequence, accurate authentication cannot be performed.